The disclosure relates generally to firearms, including devices for aiming a firearm. More particularly, the disclosure relates to live ammunition containing a battery, a positional switch, and a laser module that emits electromagnetic radiation only when inserted in the chamber of a firearm held at a non-vertical working angle.
Firearms are traditionally aimed using iron or telescopic sights mounted parallel to the bore of the firearm. To use such sights, the firearm is brought to just below the line of sight and the sights engaged by the shooter's eye. Discharging the firearm while the sights are aligned with the target will theoretically guide the shot to the point of aim. Such sights facilitate accurate aiming and shot placement when properly lined up with the target because the bore of the firearm should be aligned with the target as well.
However, iron and telescopic sights are subject to several deficiencies that have plagued shooters through the years. For example, such sights may not be visible or useful in low light or dark environments, are prone to misalignment, and can be easily damaged or rendered useless by low-force impacts. Such sights can also be difficult and slow to align, which may be particularly detrimental to a shooter in a life-threatening or stressful situation. In such scenarios, even properly calibrated traditional sights are of little to no value. It is therefore common for shooters operating in combat, close quarters and life-threatening or otherwise stressful situations to completely ignore their sights. Instead, such shooters visually focus on the threat presented by an aggressor or other target and rely on a combination of instinct and hand-eye coordination to align the firearm with the target. Even so, most shooters statistically miss more than half of shots fired at an average distance of less than seven feet.
The same is also true in the case of shotguns, wherein the average distance of most shots is less than ten yards. This is due in part to the common but inaccurate assumption that shotgun pellets will spread to encompass whatever is within the shooter's vision. For this reason, many shooters often point a shotgun toward the target rather than aim, possibly even firing from below their line of sight. To the contrary, shot spreads approximately one inch per yard when fired from the muzzle of a shotgun. Thus, a target perceived as impossible to miss across a room at 21 feet may easily be missed by the seven-inch shot pattern.
Some more modern sighting systems rely on battery-powered laser devices to assist with aiming and shot placement. Such devices typically emit an extremely straight laser beam that is generally invisible from the sides and that culminates in a bright dot on the target. A shot fired from a weapon equipped with a properly installed laser device should theoretically contact the intended target at the point illuminated by the laser when fired.
Most laser-based sighting systems attach to the exterior of a firearm and are activated by the operator through various types of switches. These kinds of laser devices add weight, bulk and an additional layer of complexity to a firearm, all of which are undesirable and require additional time to navigate. Complexity tends to increase the chance of user error, delay, and risk of failure by interfering with normal firearm operation and slowing a shooter, particularly during high-stress situations. Moreover, such systems generally must be zeroed for accuracy before they can be used reliably. Although some light-weight, pre-zeroed laser-based sighting systems that allow for internal installation are available, such laser devices are costly, often require professional installation, and must be manually switched on or off as needed to preserve battery life and mask a shooter's location.
The present inventor's U.S. Pat. No. 8,544,203, the entire disclosure of which is hereby incorporated by reference herein, discloses a sighting device for firearms comprising a laser module, battery, and associated circuitry housed within a live ammunition cartridge that projects a bright dot of light out of the bore of a firearm directly onto the target. The device is installed and the laser simultaneously activated when the cartridge is chambered in a firearm designed to accept said cartridge. It requires no zeroing or additional training beyond basic firearm safety, adds no weight to a firearm, and is affordable to most firearms owners. Removing the device from the chamber of the firearm deactivates the laser. The device can be safely stored in the magazine of the firearm or separately from the firearm when not in use.
However, the device disclosed in U.S. Pat. No. 8,544,203 is not suited for continued storage in the chamber of a firearm because the laser will continue to emit visible light until the battery is exhausted or the cartridge is removed. The fact that the device must be removed from the chamber to deactivate the laser and preserve battery life makes it unsuitable for use in certain applications such as home defense where shooters prefer to store a firearm with a cartridge chambered in order to save time and thus lives.
This deficiency forces a shooter to choose between storing the firearm with a cartridge chambered or chambering a cartridge as needed. Neither option is desirable or acceptable. Storage of a firearm with the cartridge chambered risks that the battery will be depleted and the laser rendered useless before the firearm is needed. By contrast, chambering a cartridge on an as-needed basis risks exposure of the shooter to an adversary because the act of chambering a cartridge generally creates a distinctive audible noise that could reveal the position of a shooter as well as the fact that the shooter is armed. The extra step of chambering a cartridge in an emergency also unnecessarily slows target acquisition and thus limits the shooter's responsive capabilities.
Therefore, a need exists to provide an improved laser sighting system that can remain in the chamber of a firearm stored at the ready without negatively impacting battery life. Further, a need exists to provide an improved laser sighting system that can be automatically activated through a natural motion inherent to firearm use that does not require the shooter to manually operate a separate activation switch. Still further, a need exists to provide improved laser aimed firearms ammunition that can be reliably stored for prolonged periods loaded in the chamber of a firearm and silently activated without giving away a shooter's position.